A Hepatic Impairment Study for PF-04965842.

A minimum of 24 subjects with normal, mild or moderate hepatic function will be enrolled into
the study, with approximately 8 subjects in each cohort. The Child Pugh classification score
will be utilized to assess entry criteria and to assign subjects into the appropriate hepatic
impairment group. For individual subjects, the total maximum duration of study participation
from the Screening visit to the end of clinical research unit (CRU) stay is approximately 31
days and approximately 63 days from the Screening visit to the Follow up contact.

Inclusion Criteria:

- Body mass index (BMI) of 17.5 to 40 kg/m2; and a total body weight >50 kg (110
pounds).

- Subjects who are willing and able to comply with all scheduled visits, treatment plan,
laboratory tests, and other study procedures.

Additional Inclusion Criteria for subjects with hepatic impairment:

- Satisfy the criteria for Class A or Class B of the Child Pugh classification (mild:
Child Pugh Scores 5 to 6 points, and moderate: Child Pugh Scores 7 to 9 points),
within 14 days of investigational product administration.

- A diagnosis of hepatic dysfunction due to hepatocellular disease (and not secondary to
any acute ongoing hepatocellular process) documented by medical history, physical
examination, liver biopsy, hepatic ultrasound, computerized tomography scan, or
magnetic resonance imaging (MRI).

Exclusion Criteria:

- Subjects with clinically significant infections within the past 3 months (for example,
those requiring hospitalization, or as judged by the Investigator), evidence of any
infection (including influenza) within the past 7 days, history of disseminated herpes
simplex infection or recurrent (>1 episode) or disseminated herpes zoster.

- Subjects with a malignancy or with a history of malignancy, with the exception of
adequately treated or excised non metastatic basal cell or squamous cell cancer of the
skin or cervical carcinoma in situ.

Additional exclusion criteria for subjects with hepatic impairment:

- Hepatic carcinoma or hepatorenal syndrome or limited predicted life expectancy
(defined as less than 1 year).

- Subjects who have previously had a transplanted kidney, liver, or heart.

- At Screening, persistent severe, uncontrolled hypertension.